Shell is considering quitting the London Stock Exchange as chief executive Wael Sawan confirmed the company is keeping its options open.
In what would be the biggest blow to UK's stock market thus far, Sawan told Bloomberg: "I have a location that clearly seems to be undervalued."
The energy giant is the biggest London-listed company - worth around £168bn - in an index traditionally dominated by oil and gas companies.
Sawan said he's looking at "all options", leaving to door open to potentially quit the UK for the US.
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Ashley Kelty, head of oil and gas research at Panmure Gordon, said the Shell chief's comments reflect the differening perceptions of oil and gas in Europe compared to America.
"Americans are far more positive towards oil and gas than Europeans. They don’t see it as being the great evil that is perceived to be here, and the tax regime is more supportive."
The future tax outlook for oil and gas companies is bleak, especially if a Labour-led government is to be formed.
It would see an increased and extended windfall tax on oil and gas profits, while investment allowances would be removed.
Kelty added: In New York, [Shell] won’t come under the same amount of pressure around the environment and greenwashing - they will be allowed to get on with what they do.
"If they do go, it would suggest they want to row back on the renewable side even farther than they’ve admitted previously because [in Europe] they will get penalised.
Should Shell wish to move their primary listing away from London, they would require 75% approval in a shareholder vote.